Copying-sheet



UNITED STATES PATENT OFFICE.

I-IOIVARD IV. BROWN, OF OAKLAND, CALIFORNIA.

COPYING-SHEET.

SPECIFICATION forming part of Letters Patent No. 409,826, dated August2'7, 1889.

Application filed October 14, 1887. Serial No. 252,376, (No specimens.)

T0 aZZ whom it may concern.-

Be it knownthat I, HOWARD WV. BROWN, a citizen of the United States,residing in Oakland, in the county of Alameda and State of lalifornia,have invented a new and useful Portable Copying-Sheet, of which thefollowing is a specification,

My invention relates to improvements in copying-sheets for letters,circulars, and other written matter. I generally employ paper of aboutthe thickness and quality of light co1nmercial note-paper. I prepare thesurface with a thin coating, smoothly laid on, about the thickness of anordinary coat of varnish or paint, of the following compound: Tothreepounds of glycerine, one pound of gelatine, one pound of water, threeounces of glue, four ounces of alum,which I dissolve and combine byplacing in a vessel over steam heat and stirring carefully until aperfect mixture. I spread this upon the surface evenly in a thin coat. Ithen further perfect the surface by sifting over the surface afinely-pulverized compound of lyeopodium and alum, in proportion ofonefourth ounce of alum to two ounces of lycopodimn.

This compound is gradually incorporated with the coating, and produces asoft, velvety surface, which remains in a dry and still very yieldingand elastic state. Two of these surfaces may be placed together Withoutliability of sticking, even in the hottest climate. \Vhen used forcopying, the surface is washed off with a soft wet sponge, and as soonas dry the surface is ready to apply the letter, circular, or otherwriting or drawing to be copied. With good aniline ink a hundred or morecopies may be made clear and distinct from one sheet thus prepared. Iprepare these sheets either from sheets already the size required forletters, &c., or from roll-paper and cut afterward to the required size.I generally produce these sheets in a book form for the retail trade,each sheet forming a leaf, to be torn out when used, in the same manneras the letter-sheet is taken from the ordinary and is never liable togranulate or crack, and insures portability.

I am aware that my invention may be employed Where other material thanthe thin paper is used for a portable copying-sheet or plate, as thesoft dry surface described is of great advantage, even where muchthicker or heavier sheets or plates are used.

It will not crack or granulate, and remains pliable even when exposed tothe atmosphere for a great length of time, as I have tried it forseveral months without seeing any decrease in its value as acopying-sheet.

When French chalk is used, its effect upon the composition is onlytemporary, as it absorbs all the moisture of the compound and a chemicalchange takes place in which the sheet becomes hard, dry, and granulated,causing it to rapidly deteriorate and in a short time become totallyunfit for use, while by the employment of powdered lycopodium. and alumcombined the copying-sheet is preserved .in a pliable and moist stateindefinitely, and I have found by experience that lycopodium, whencombined with alum, is the only substance which produces this result andis permanent in its effect. The lycopodium enters the composition, and,filling the pores, hermetically seals the surface, which entirelyprevents the evaporation of moisture and is of the utmost importance.The lycopodium produces a soft, smooth surface, prevents the stickingtogether of the sheets when placed face to face, and acts as apreservative, while the alum acts as an astringent and serves thepurpose of toughening and hardening the surface, causing the same tobecome firm and compact.

I am aware that it is not new to use glycerinc and gelatine with water,and that alum has been used in this connection to prevent the sheetsfrom being sticky. I am also aware that a coloring-powder has been usedwith such; but I am not aware that any one has heretofore made acomposition of glyeerine, gelatine, water, glue, and alum for thepurposes specified, and another composition of alum and lycopodium to beused in connection with the first-named composition; and I am.furthermore not aware that any one has used all of the ingredients inthe proportions combined in the proportions specified, and on stated.

this a surface-coating of pulverized alum and [o Having-thus describedmyinventiomwhat I lycopodium, as set forth.

clai1n,and desire to secure by Letters Patent,

' 7 T T T 5 is, in copying sheets I IIOW'ARD ll. BROWL.

As an improved article of manufacture, a *itnesses: copying-sheet havingan absorbent coating of H. E. PARRY,

glycerine, gelatinc, water, glue, and alum, O. HOPPE.

